So this may seem like a weird topic but lately I've been playing Wolfenstein New Order (very fun game btw) and I get this odd feeling of satisfaction when the player kills a nazi or any other bad guy in the game, same feeling with games like Doom 4, Brutal Doom, Manhunt, etc. Anyone know any games like this where the player can brutally slaughter enemies who are obviously bad guys or monsters?

Witcher 3 has an easy combat mechanic, but enemies only come in smallish packs and the world is extremely large. Bayonetta and the Devil May Cry series are hack and slash games, though I haven't played them so I don't know if your character has morally questionable enemies.

Without strife, your victory has no meaning. Without strife, you do not advance. Without strife, there is only stagnation